Ethylene and propylene (light olefins) are commercially important chemicals. Ethylene and propylene are useful in a variety of processes for making plastics and other chemical compounds.
The prior art is always looking for more efficient ways to produce greater yields of light olefins, and especially propylene, from hydrocarbon feed materials.
One important source of light olefins is based on the pyrolysis, e.g., the steam and catalytic cracking, of selected petroleum feed materials. These procedures also produce significant quantities of other hydrocarbon products.
Another, more recent source of light olefins is the oxygenate to olefins conversion process and specifically the methanol-to-olefins (MTO) process.
The MTO process is more effective in producing light olefins than conventional hydrocarbon pyrolysis systems.
Instead of using a hydrocarbon source, this process is based on converting an oxygenate, such as methanol, ethanol, n-propanol, isopropanol, methyl ethyl ether, dimethyl ether, diethyl ether, di-isopropyl ether, formaldehyde, dimethyl carbonate, dimethyl ketone, acetic acid, and mixtures thereof, and preferably methanol to olefins in the presence of a molecular sieve catalyst.
Presumably, the disparate nature of the feed materials utilized in these two sources of light olefins, as well as the compositional differences in the respective reaction products discharged from these separate processes have prevented the prior art from considering the advantages of integrating these separate syntheses.
The present invention focuses on an improved light olefins synthesis process created by a judicious integration of an oxygenate to olefin conversion system (MTO) with a hydrocarbon pyrolysis system.